Preterm birth is a major medical problem of increasing incidence, and xenobiotics may contribute. The long-term goal of this project is to discover xenobiotics that contribute to preterm birth. Environmental and biological samples will be tested, and these samples will mostly come from Puerto Rico because of the unusually high incidence of preterm birth there. While nontargeted (screening) analysis will be conducted, primary attention will be given to Superfund and related contaminants, since there are many Superfund sites in Puerto Rico. Much of the analysis will be based on mass spectrometry (MS); three types of MS will be employed: (HPLC)MALDI-TOF/TOF-MS, GC-EI(EC)-TOF-MS, and HPLC-ESI-TOF-MS. We will seek to discover putative PTB-xenobiotics, defined as xenobiotics that meet either one of the following two criteria: they correlate with preterm birth, or they do not but are common as contaminants and have a bioactivity that could contribute to this condition. The environmental samples will be tap water and ground water, including samples that have been remediated (detoxified) by electrolysis. The biological samples will be pregnancy tissues (gestational membrane, placenta), cell cultures, peripheral blood leukocytes and urine. The pregnancy tissues will come from rats and humans, and the leukocytes and urine will come from humans. One or more of four kinds of assays will be applied to each of these types of samples: 1. Direct Detection, the xenobiotic (or a laboratory derivative thereof) is directly detected in a mass spectrometer; 2. DNA Adduct, the xenobiotic forms a DNA adduct in vivo that is detected by Mass Tag Profiling; 3. Pro-oxidant, the xenobiotic is detected after metabolism-like oxidation in a Nucleotide Exposure Assay; 4. Bioassay, the xenobiotic is detected in a bioassay with cultured cells derived from human placentabased initially on monitoring for cytotoxicity (primary screen) and subsequently for apoptosis, genotoxicity, inflammation, and oxidative stress (secondary screen, reflecting mechanisms that could contribute to preterm birth). New or improved analytical methodology will be developed, and new combinations of methodology will be studied in this project to enhance the discovery of putative PTB-xenobiotics by these four strategies. The project, thereby, will result in generally-applicable advances in the overall field of discovering toxic xenobiotics in complex samples. Through exchange of samples, collaborative testing, and collaborative analysis of data, either directly or through the cores, this project integrates with all of the other projects in the PRoTECT program.